Soil aeration devices are used to penetrate the soil so as to allow the roots of plants to breathe and to simulate decomposition of organic matter. Aeration is particularly helpful in treating lawns that have become thatched or covered with a dense layer of growth or accumulated clippings that prevent the air from coming in contact with the soil. Aerator devices typically have spikes mounted on a rotatable drum or roller, the spikes penetrating the soil when the drum is propelled along the surface.
Various approaches for mounting and arrangement of spiked drums on lawn mowers and tractors are shown in prior patents. U.S. Pat. No. 4,899,828, issued Feb. 13, 1990, to Harris, discloses mounting of a spiked roller on supporting arms extending out past the front of the lawn mower, the support arms being oriented to the ground at an angle between 30 and 60 degrees. This arrangement is said to force the spikes into the ground without use of ballast weights. Other patents, exemplified by U.,S. Pat. No. 2,912,813, issued Nov. 17, 1959, to Ellsworth; U.S. Pat. No. 2,483,846, issued Oct. 4, 1949, to Roche et al.; and U.S. Pat. No. 2,476,084, issued July 12, 1949, to Cour, disclose use of a spiked roller arrangement on reel-type lawn mowers, the rollers replacing or being placed behind the usual roller at the back of such mowers. The Ellsworth patent further shows a roller device having a large number of coaxially aligned smooth roller segments with spiked narrow discs placed between the segments. This allows the rollers and discs to rotate freely in either direction independent of one another and keeps the spikes from digging in when the mower is moved in a curved line. A tractor-mounted device using a plurality of independently mounted, longitudinally spaced-apart roller segments is disclosed in U.S. Pat. No. 3,650,331, issued Mar. 21, 1972, to Dedoes. This structure permits independent vertical movement of the segments relative to one another and provides for better coverage of high and low spots on rough ground.
The prior patents do show an aerator mountable on the front end of the lawn mower of a riding mower in a manner such that the mower may be turned and maneuvered in corner areas without digging in of rollers spikes. It is desired to provide such capability along with enabling a propelled, spiked roller of an aerator device to adjust its own path in a desired direction.